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Tricopter Yaw issues (APM)

iJedi

Junior Member
#1
I have recently built a tricopter that has been flying well in stability mode until the past couple short flights. It now constantly turns to the left (yaw axis) now and I can still control it but I have to correct for left spin.

I am using the APM 2.5 (hobbyking version) with an external GPS/compass (turnigy).

I have recalibrated the compass multiple times and it still turns left consistently. I could try trimming it to the right (a lot) but it seems like there must be a calibration or setting that I have set incorrectly.

Does anyone have any ideas of what might be causing this? I didn't know exactly what details might be pertinent so ask if I missed any specifics.

Calibrating the APM 2.5 compass with Mission Planner has been hit and miss. Most tries it will give me offsets in extreme numbers and will not arm because the "compass offset is too high". Sometimes it gives decent offsets but it never is satisfied with the number of data points it collects.

Any help is appreciated.

Mark
 

iJedi

Junior Member
#3
It isn't tilting at all it is spinning. It stays level and lifts off the ground fine but it is spinning while it lifts. Another forum suggested I re-calibrate the gyros too though so I guess it can't hurt to try.
 

stay-fun

Helicopter addict
#4
Oh oops! I misread that. Sounds like an issue with your yaw servo. Make sure it goes into the direction it's supposed to, and check if the servo gears are still ok.

As far as I know, a gyro is used to detect yaw motion, not the compass. So fiddling with the compass won't help. I would even suggest to remove any unnessecary components until the copter flies as it should. When it does fly well, you can make things more complicated.
 
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iJedi

Junior Member
#5
I removed the GPS/compass and it still yaws to the left. I noticed that it does it drastically at take off but once I get it up in the air a bit it is only slight. Still annoying to compensate for. I know that the servo direction is correct because when it is backwards it spins out of control trying to correct the with the wrong direction. This is still flyable it just feels like it needs to be trimmed but you aren't supposed to trim multirotors from the transmitter.
 

stay-fun

Helicopter addict
#6
I had it once with a helicopter that there was a tail drift. Turned out my transmitter had different trim settings for different flight modes, and I was always setting up the heli in throttle hold. I accidentally bumped the trim in flight.

So check the yaw output from the transmitter in neutral, and check in the software what your flight controller is seeing as yaw input.

If it's not that, then the problem beats me. Anyone else?
 

x0054

Senior Member
#7
Have you recalibrated the Gyro and Accelerometer, and have you recalibrated the Radio on the APM. On the APM you can calibrate the radio inputs, and set the midstick position. Maybe your midstick setting is out of whack. Try recalibrating all of the radio channels and see if that helps.